1. Field of the Invention
The present invention generally relates to a motor of a ceiling fan and, more particularly, to a motor able to receive a plurality of bearings by one bearing sleeve.
2. Description of the Related Art
Referring to FIG. 1, a conventional motor of a ceiling fan, with a reference number of “9,” of U.S. Pat. No. 7,615,898 entitled as “INTEGRATED STATOR AND ROTOR FOR A DC BRUSHLESS CEILING FAN MOTOR”, is shown and includes a stator 91 and a rotor 92. The stator 91 has a core 911, a plurality of coils 912 wound on the core 911, and a shaft 913 passing through the core 911. The rotor 92 has an upper shield 921, a lower shield 922 and a waist ring 923 sandwiched by the upper and lower shields 921, 922. Each of the upper and lower shields 921, 922 combines with a bearing 924 for the shaft 913 to couple with, and the stator 91 is received in a room defined by the upper shield 921, the lower shield 922 and the waist ring 923.
Specifically, since the rotor 92 couples with the shaft 913 of the stator 91 via the bearing 924, the shaft 913 has to connect with the bearing 924 by a press fit, so that the rotor 92 can rotate around the stator 91 stably and so that an inner ring of the bearing 924 cannot rotate relatively to the shaft 913. In other words, the bearing 924 has to be mounted onto the shaft 913 by a huge pressure in manufacture to achieve the press fit condition between the shaft 913 and bearing 924, and, thus, a special machine or time-consumptive procedure to produce this huge pressure is required. Therefore, the process for manufacturing the motor 9 is thus complicated and time consumptive. Besides, the awkwardly big-sized motor 9 also increases the difficulty in assembly and thus raises the manufacture cost.
Moreover, the vibration caused by the operation of the rotor 92 can easily transmit to the shaft 913 via the bearing 924 due to the press fit between the shaft 913 and the bearing 924, and thus affects the electronic members inside the stator 91 or other members connecting with the shaft 913. This vibration may therefore largely raise the failure rate of these members, and further decrease the lifetime of the motor 9.
In sum, there are drawbacks such as a complicated manufacture process and a short lifetime of the motor 9, and, thus, an improved motor for ceiling fan is required.